From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Tue, 18 Dec 2007 12:22:13 +0100
Subject: [lockdep] mismatched lockdep_depth/curr_chain_hash
Message-id: 20071218112316.357856238@chello.nl
O-Subject: [RHEL5.2 PATCH 12/14] lockdep: fix mismatched lockdep_depth/curr_chain_hash
Bugzilla: 193729

It is possible for the current->curr_chain_key to become inconsistent with the
current index if the chain fails to validate.  The end result is that future
lock_acquire() operations may inadvertently fail to find a hit in the cache
resulting in a new node being added to the graph for every acquire.

Signed-off-by: Gregory Haskins <ghaskins@novell.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/kernel/lockdep.c b/kernel/lockdep.c
index 1fb2d90..984e1e3 100644
--- a/kernel/lockdep.c
+++ b/kernel/lockdep.c
@@ -2274,7 +2274,6 @@ out_calc_hash:
 	}
 #endif
 	chain_key = iterate_chain_key(chain_key, id);
-	curr->curr_chain_key = chain_key;
 
 #ifdef CONFIG_PROVE_LOCKING
 	/*
@@ -2322,6 +2321,7 @@ out_calc_hash:
 	}
 #endif
 
+	curr->curr_chain_key = chain_key;
 	curr->lockdep_depth++;
 	check_chain_key(curr);
 	if (unlikely(curr->lockdep_depth >= MAX_LOCK_DEPTH)) {